Method for the automatic control of aviation engines



Feb. 12, 1935. E. SCHIMANEK METHOD FOR THE AUTOMATIC CONTROL OF AVIATION ENGINES Filed NOV. 11, 1932 Patented Feb. 12, 1935 1,991,296

UNITED STATES PATENT OFFICE METHOD FOR THE AUTOMATIC CONTROL OF AVIATION ENGINES Emil Schimanck, Budapest, Hungary, assignor to Societe Du Carburateur Bleriot, Paris, France Application November 11, 1932, Serial No. 642,315 In France July 2, 1932 6 Claims. (Cl; 137-453) It is known that the power of aviation engines a part in section showing an improved carburettor varies with the flight altitude, the barometric according to'the present invention; pressure and the temperature, and therefore with Figure 2 is an elevation of the carburettor the specific weight of the air. This variation in showing an axial section; specific weight manifests itself in two ways: Figure 3 shows a modified form of construction 5 1. By altering the supply to the cylinder; of the corrector indicated in Figure 1. 2. By altering the mixture at the carburettor. The automatic altimetric corrector fitted for -It is known that this first alteration is remedied example to a carburettor such as the one de-. either by employing a compressor or by emscribed in French Patent No. 611,742 in the champloying a larger cylinder in combination in both her 5 of which there is a constant pressure which In cases with the necessary throttling of the inis below atmospheric pressure is formed by a duction pipe. cylinder 1 in which moves a piston 2. Atmos- With regard to the second alteration or change, pheric pressure exists at the outer side of the it is known that, in order to prevent this, the piston.

v carburettor setting is altered. 0n the other side of the piston in the chamber 13 The subject of the present invention is a meth- 4 there exists the pressure of the chamber 5 0d permitting such adjustments to be made by that is to say a pressure which is lower than atan automatic control, that is to say both the mospheric and which is constant. The rod 6 of throttle adjustments and the carburettor setting the piston 2 moves in the body 7 and acts as a (correction). controlling member for'a servo-motor with re- 20 The mehod consists essentially in the use of a spect to the atmospheric pressure because the vacuum for actuating a servo-motor producing weight of the piston 18 of the carburettor is kept the adjustments mentioned above the vacuous in balance by this low pressure. condition being provided by the carburettor of The servo-motor is formed by the piston 8 I 5 the type, for instance, as that described in Gern d in the y 7. This piston is loaded 5 man Patent No. 422,479. by the spring 9. The pressure of the spring may The vacuum mentioned above is utilized for be varied by rotating the l 10 which is 6011- maintaining an auxiliary liquid under a constant neeted t0 the body '7 We screw thread. not shown. pressure, which pressure is always balanced by y meving wa ds h e the o e 1 0 the external atmospheric pressure and by the adthe regulating piston 6 becomes situated in front 30 ditional use of a, spring, diaphragm or imil r of the aperture 12, oil under pressure can act member. upon the piston 8 by passing through the hole The variation in atmospheric pressure pro- 12, the aperture 11 and the channel 13. Further, duces a movement of the member which h d, it during this movement towards the right the 5 hitherto been kept in equilibrium in particular terminaled 14 0f h p sto 2 uncovers th by this atmospheric pressure but after a certain aperture 15 0f t e c a el. The oil which is movement the deformation of the spring or of the ineohtaet w the piston will flow through h similar members arrest this movement by re-esl tablishing the equilibrium Thesemovements The movement of the piston 8 is transmitted o and these deformations which may be uniformly by the rod i to the lever 17 which in its tum regulated by calibrating the spring may thus b? makes the piston 18 of the carburettor turn. employed for controlling a correcting member The operation of the servo motor is as follows. In the two cases mentioned at the commence- 3 g' g g f the gg g gz f i s fi aexs ,eween ecam r an ecamthe descmtmn' that when ber 4, the piston 2 is pushed with a constant force 45 lating the supply to the cylinders of when regutowards the left. This force, divided b the se lating the mixture at the carburettor the regution of the piston 6, gives the (Distant lating member (throttle valve etc.) is actuated pressure that will be produced behind the piston by the f Put mte eY The difference between the total oil pressure and ,60 The muewing deselipuen given by Way of the external atmospheric pressure on the piston 8 ample with reference to the accompanying drawis borne by, t mi 9,

mg will enable the manner in which the inven- If the aeroplane now rises the atmospheric tion can be car ed 0 fO b c ea y underpressure falls; the difierence between the external stood. atmospheric pressure on the one hand and the I Figure 1 is aplan' view th a part removed. and unchanged oil pressure existing behind the pis- I ton 8 onthe other hand" is therefore equal to the difference between the atmospheric pressures at the altitude in question, and on the ground.

The oil pressure pushes the piston 8 towards the left, that is to say towards the outside. Consequently the spring 9 is further compressed. It is calibrated in such a way that, for a given atmospheric pressure for example 0.5 atmospheres, it becomes compressed by an amount corresponding exactly to the amount the piston 8 must move towards the left in order to give the piston 18 an angular position which gives a perfect adjustment for the atmospheric pressure in question. The piston 8 is .connected to the piston 18 by means of the rod 16 and the lever 17.

The constant oil pressure behind the piston 8 is obtained by the fact that a by-pass of the oil circulation of the engine is mounted on the union 12. If the pressure per unit area behind the piston 8 is less than the pressure which the piston-2 imparts to the rod 6, a force directed towards the left is produced and the piston 2 moves towards the left until the hole 11 has reached the aperture 12. The oil at higher pressure then enters through the connection 12 until the pressure produced overcomes the force acting towards the left on the piston 2, and moves the latter towards the right,. thus separating the orifice 11 from the aperture 12. The admission of oil is then cut off.

On the other hand, if the oil pressure behind the piston 8 is too great, it causes the piston 2 to move towards the right. The edge 14 of the piston rod 6 then opens the outlet 12 and the oil pressure falls.

It is thus seen that this to and fro movement produces a constant oil pressure behind the piston 8.

The constant force urging the piston 6 to the left is obtained in the constructional form illustrated in Figures 1 and 2 by securing to the rod 6 a piston 2, movable in a cylinder 1. The outer or right-hand face 3 of the piston 2 is open to the by the difference in pressure between the air above it and the air below it. Since the weight of the piston does not alter, the pressure difference remains constant. Consequently the difference between the air pressure on the two sides of the piston 2 is also constant, thereby providing a constant force urging the rod 6 to the left.

Figure 3 illustrates a. different method of obtaining this constant thrust. Here the rod 6 terminates in a piston 19, corresponding to the piston 2 of Figure 1, but working in a cylinder closed at both ends. The left-hand cylinderspace 4 is open to the atmosphere at 24, but the right-hand end is filled-with liquid and communicates with a vertical tube 25, terminating at the top in a small open reservoir 26. The mean absolute pressure of the liquid against the piston 19 is determined by its head It plus the atmospheric pressure acting upon the free surface of the liquid in the reservoir 26; but since atmospheric pressure alsoacts through the tube 24 on the other side of the piston 19 the net force acting to the left is equal to the hydrostatic pressure resulting from the head h. The reservoir 26 serves, to keep the head h substantially constant notwithstanding movements of the piston .19.. This form of construction could of course ,only be used on aircraft e. g. airships flying mainly in a substantially horizontal position.

The constant force urging the rod 6 to' the left i may alternatively be obtained by other means, for instance by connecting with the right-hand or= left-hand side of the piston 2 or 19 any other raised or lowered fluid pressure either normally available or expressly provided for the purpose and differing from the pressure of the surrounding atmosphere by a constant amount.

In the case when the supply to the cylinders has to be regulated and not the mixture to the carburettor, the regulating member may naturally be connected to the controlling throttle valve.

What I claim is:

1. An apparatus for controlling the power out-. put of aircraft engines in dependence on atmospheric pressure comprising a regulating member, a controlling member, a chamber between said members, a fluid under pressure in said chamber and acting on both members to urge the latter in one directiomthe regulating member being acted on and urged in the opposite direction by atmospheric pressure, a constant force acting on the controlling member urging the latter in the opposite direction, said controlling member controlling the admission and discharge of the pressure fluid to said chamber, said controlling member operating when the pressure of said fluid falls to admit more pressure fluid to said chamber and operating when the pressure of the fluid increases to discharge the latter, said controlling member cutting off the admission and discharge of the pressure fluid when normal pressure of the latter is re-established.

2. An apparatus as claimed in claim 1 characterized by the provision of spring means resiliently acting on ,the regulating member to' maintain the latter in equilibrium when it is displaced by a change in atmospheric pressure.

. 3. An apparatus as claimed in claim 1 characterized in that said constant force is constituted by a pressure having a value different from atmospheric pressure. I

4. An apparatus as claimed in claim 1 characterized in that said constant force is constituted by the constant partial vacuum existing in the carburettor of the engine.

5. An apparatus as claimed in claim 1 characterized in that said constant force is constituted by a column of liquid.

6. An apparatus as claimed in claim 1 characterized in that said regulating and controlling members are constituted by pistons, the controlling piston being provided with a rod acting as a slide valve controlling the admission and discharge of the pressure fluid.

. EMIL SCHIMANEK. 

